Muscle cells from embryonic normal and genetically dystrophic chickens are to be grown in culture, (a) to compare the relative rates of myofibrillar protein synthesis and degradation; and (b) to provide an in vitro assay system in which to further investigate the potential efficacy of specific drugs with various modes of action upon muscle growth, histochemistry, and protein turnover. Specific agents to undergo study include proteolytic inhibitors, branched-chain amino acids, anti-serotoninergic compounds, steroidal and non-steroidal anti-inflammatants, and antagonists to calcium flux. Individual drugs from the latter pharmacological classes have each been shown previously to relieve some of the many in vivo dystrophic symptoms exhibited in one to three-month old genetically dystrophic chickens. Significant degrees of benefit have included: prolonged functional ability, improvements in blood enzyme and metabolite levels, increases in wet weight, non-collagen protein, and reductions in the histopathological features of the affected pectoralis major and minor muscles.